Type printing telegraph apparatus



Nov. 12, 1963 A. w. WALLENS 3,110,765"

TYPE PRINTING TELEGRAPH APPARATUS I Filed Aug. 25. 1961 3 Sheets-Sheet lFIGJ.

ANTHONY W. WAL LENS A Home Nov. 12, 1963 I w. w 3,110,766

TYPE PRINTING TELEGRAPH APPARATUS Filed Aug. 25. 1961 s Sheets-Sheet 2Inventor ANTHONY W. WALLEA/S Nov. 12, 1963 A. w. WALLENS 3,110,766

TYPE PRINTING TELEGRAPH APPARATUS Filed Aug. 25, 1961 3 Sheets-Sheet 3Inventor ANTHONY V. WALLENS At orne United States Patent 3,110,766 TYPEPRINTING TELEGRAPH APPARATUS Anthony Walter Wallerrs, Croydon, Surrey,England,

assignor to Creed & Company Limited, Croydon, Eng

land, a British company Filed Aug. 25, 1961, Ser. No. 133,949 Claimspriority, application Great Britain Sept. 2, 1960 16 Claims. (Cl.178-45) The present invention relates to type printing telegraphapparatus and more particularly to a type printing telegraph apparatushaving a movable type printing head.

An object of the present invention is to provide an improved typeprinting apparatus wherein the effective mass of the carriage and theprinting head thereon is reduced and wherein the carriage and printinghead may be moved in predetermined step-by-step fashion.

The type printing head concerned in the present invention includes atype printing head mounted on a carriage, a lead-screw means which isrotatable by the motion of the carriage, a ratchet wheel atfixed to thelead screw, pawl means alternately engaging and disengaging said ratchetwheel to permit stepby-step movement of the carriage, and a head-feedselector means for operating said pawl means to permit said step-by-stepmovement.

The present invention is described with reference to the accompanyingdrawings in which:

FIG. 1 shows a perspective View of a pant of a type printing telegraphapparatus according to the invention.

PEG. 2 shows a pant sectioned view of pawl means forming part of theapparatus of FIG. 1.

FIG. 3 shows a part sectioned view of head-feed selector means formingpart of the (apparatus of FIG. 1, and which is operatively associatedwith the pawl means of FIG. 2.

FIG. 4 shows in greater detail a part sectioned view of power-drivenbelt means incorporated in the apparatus of FIG. 1 for driving acarriage and a type printing head mounted thereon.

FIG. 5 shows a part sectioned View of carriage-return selector meansforming part of the apparatus of FIG. 1 and which is operativelyassociated with type-printing head position indicating mean-s of FIG. 1,the power driven belt means of FIGS. 1 and Zj'and the pawl means of FIG.2.

Referring now to FIG. 1 which shows an embodiment of the apparatusaccording to the present invention, a type printing head 1 isaccommodated on a carriage 2 which carriage is arranged to be moved onrollers such as 3 engaging rails 4, in the letter-feed andcarriage-return directions indicated by the arrow A and B respectively,these movements are effected by power-driven belt means which is laterto be described. 7

A lead-screw 5 engages a threaded hole through an extending portion 6 of the carriage 2 and is supported at its ends by means not shown. Thehelix angle of the thread of the lead-screw 5 and that of the matingthread in the hole through the extending portion 6 of the carriage aresuch that movement of the carriage in the letter-feed andcarriage-return directions, will cause the lead-screw 5, and inconsequence a ratchet wheel 7 affixed thereto at one end, to rotate inthe directions indicated by the arrows C and D respectively.

Pawl means such as is shown in part section in FIG. 2 is utilised topermit step-by-step movement of the carriage 2 (FIG. 1) by thepower-driven belt means in the letter teed direction. In this figure anend view of the ratchet-wheel 7 is shown in which two pawls 9 and 19 aredisposed in the path of teeth such as 11 of the ratchet wheel 7, whichratchet wheel is arranged in such a manice ner with respect to the pawlsthat in successive movements of both pawls together into the path of theteeth, the pawls engage a tooth of the ratchet wheel alternately. Thepawls 9 and 10 are housed respectively in carriers 12 and 13 which arearranged to pivot on pins 14 and 15 respectively, compression springs14A and 15A are provided to engage carriers 12 and 13 respectively forcausing the pawls 9 and 10 to be biased to move in the directionsindicated by the arrows E and F respectively, i.e. into the path of theteeth of the ratchet wheel.

Shock absorbing devices 16 and 17 of conventional design may be utilisedto absorb the shock of engagement of the paw ls 9 and 16 when one or theother of them engages with a tooth of the ratchet wheel. The ends ofpawls 9 and 10 are arranged to engage the flanged ends of operatingspindles 18 and 19 of the shock absorbing devices with which they arerespectively associated. Hydraulic means inthe form of cylinders 20 and21, and pistons 22 and 23 and pistons 24 and 25 slidably accommodatedwithin these, cylinders respectively, are associated with pawls 9 and 10for moving the pawls out of the path of the teeth of the ratchet wheelin directions opposite to those indicated by the arrows E and F underthe influence of a hydraulic medium such as, for

example, oil acting on the pistons, and for permitting the pawls to moveinto the path of the teeth in the directions indicated by the arrows Eand F under the influence of the spring means incorporated in the hinges14 and 15. The utilised hydraulic medium for causing movement of pawls 9and 10 out of the path of the teeth or the ratchet wheel is fed tocylinders 20 and 21 under pressure firom-a pump 8 (FIG. 5), via aprimary feed line 96, a cylinder 63 (of the hydraulic valve of acarriage-return selector means later tobe described with reference toFIG. 5) a further primary feed line 28, and secondary feed lines 26 and27 (FIGS. 2 and 5).

The utilized hydraulic medium is also fed to Cylinders 2% and 21 underpressure to perform the same functions 'from the pump 8 via the primaryfeed line 96, a cylinder feed line 96 is connected between the pump 8(FIG. 5)

and the cylinder 30. Primary feed line 94 is connected between cylinder36 and secondary feed lines 97 and 98 (FIG. 2) A sump returnfeed line 99is also incorporated between cylinder 30* and a sump (not shown) forpurposes later tofbe described. A solenoid 34 is provided with amagnetisab-le core 33 and an armature 32 to which a pin 35 is affixed atone end, and which pin engages the underside of the piston 29 by way ofa hole in the cylinder 30. A pin 36 extends through the base portion ofthe cylinder 39 to engage with its upper end the underside of the piston29 and to engage with its lower end a double lobed cam 37 mounted forrotation on a shaft 38 which is driven by a motor (not shown). Thenumber of revolutions per minute of shaft 38 is equal to half theletter-feed rate of the equipment.

Referring again to FIG. 1, the-power-driven belt means, previouslymentioned, for driving the carriage 2 and typeprinting head 1 thereon inthe letter-feed and carriage return directions comprises a belt 39 whichis afi'ixed by a portion thereof to the member 6 extending from thecarriage 2. The belt 39* is supported for movement in the :3 directionsindicated by the arrows A and B by pulleys 4t and 41.

Belt tensioning pulley 41 is free running on a member 42 which isconstrained to move in the direction indicated by the arrows K under theinfluence of tension spring 43 acting on member 42 which is pivoted on apin 44. Pulley 40 is mounted on a shaft 45 which shaft'is coupled to afirst motor 59 (FIGURE 4) to drive pulley 40 in an anti-clockwisedirection and thus the carriage 2 and type-printing head 1 accommodatedthereon in the carriage-return direction. A hydraulically operatedclutch for engaging or disengaging the drive between the aforementionedmotor and the belt by way of the pulley 49 is constituted by pressurepads 46 and 47, friction pads 43 and 4% all of which are normally freerunning on shaft 45 and which embrace pulley 40 and a gear wheel 50'affixed thereto, and a piston 51 operable to move within a cylinder 52under the influence of the utilised hydraulic medium, which is fed tothe cylinder 52 under pressure from the pump 8 (FIG. via primary feedline 96, the cylinder 63 of the aforementioned hydraulic valve of thecarriage-return selector means, and secondary feed line 53 (FIGS. 1, 4and 5).

A second motor 54 drives pulley 40, by way of coupling '55, magneticclutch 56', gear wheels 57, 58 and 59, in a clockwise direction and thusthe carriage and typeprinting head in the letter-feed direction. Theconstruction of the driving and clutching arrangements will be betterunderstood with reference to FIG. 4, which is a part sectioned view ofthe integers involved. The shaft 45 has mounted thereon, in thefollowing order, the pressure pad 46 resting against a collar 66integral with the shaft 45, friction pad 48, pulley 4t} and gear wheel'50 affixed thereto, friction pad 49-, and pressure pad 47. The exposedend of piston 51 which is operable to move within cylinder 52 isarranged concentric with shaft 45 and further arranged when operated, toengage pressure pad 47.

The aforementioned carriage-return selector means for operating thehydraulic clutch and the magnetic clutch 56 is constituted by ahydraulic valve and electric circuit means respectively which co-act inoperation. Such means are shown in part section in FIG. 5, the hydraulicvalve comprises a piston 61 supported by a spindle 62 for movementwithin the cylinder 63 of the hydraulic valve, and a compression spring64 which is housed Within the cylinder 6-3 and disposed between theupper side of piston 61 and upper head of the cylinder 63. It is thepurpose of the compression spring 64 to effect self-actuation of thehydraulic valve downward when permitted, in the direction indicated bythe arrow J, from a first condition of operation to a second conditionof operation, by means and in a manner later to be described. In FIG. 5,the hydraulic valve is shown in its non-actuated or first condition ofoperation.

Connection between the pump 8 and the cylinders 63 and 30 (FIG. 3) ofthe carriage-return and head-feed selector means respectively areestablished as previously stated by primary feed line 96. A sump returnfeed line the purpose of which is later to be described is alsoincorporated between cylinder 63 and a sump (not shown).

The electric circuit means is constituted by a pair of spring contacts65- and 66, and these contacts are electrically connected in series withthe magnetic clutch 56 (FIGS. 1 and 4) and a source of power foroperating the magnetic clutch. The aforementioned contacts are disposedabove the spindle 62 supporting piston 61. The lower contact 65 isalways engaged by the upper end of spindle 62. so that in thenon-actuated condition of the hydraulic valve i.e. in a first conditionof operation, electrical connection exists between contacts 65 and 66through their engagement. A solenoid 68 comprising a magnetisable core69 and an armature 76 and a lever 71 are utilised to permit thehydraulic valve and the electrical circuit means to selfactuate fromtheir first conditions of 4 operation to their second conditions ofoperation in response to a carriage-return signal. Referring now to FIG.1 the means for indicating a predetermined position of the type printinghead 1 during its movement with the carriage 2 in a letter feeddirection comprises a bail 76 having a number of projections 77extending from a side thereof and each of which projections has aninclined planar surface such as 78 disposed toward the right hand end ofthe apparatus and a vertical surface such as 79 disposed toward the lefthand end of the apparatus. The bail 76 is suitably mounted by means notshown to be slidable in the letter-feed and carriage-return directionsindicated by the arrows A and B respectively. Further inclined planarsurfaces 8t? and 81 are incorporated at the ends of slots 82 and 83respectively in the bail 76 and are arranged to be engaged by rollers 84and 85 which are rotatably afiixedto the apparatus frame by means notshown.

The bail is arranged to be moved during a carriagereturn movement of thecarriage 2, from a first position of operation to a second position ofoperation in the direction indicated by the arrow A by a piston 86 whichis moved in a fixed cylinder 87 under the influence of the utilisedhydraulic medium which is fed to the cylinder 87 by way of the secondaryfeed line 88 connected to the primary feed line 28 (FIG. 5) from thehydraulic valve of the carriage-return selector means of FIG. 5. Thevertical surface 89 of a projections 90 extending vertically upward fromthe carriage 2 is arranged to engage, during movement of the carriage 2in a letter-feed direc tion, the vertical surface such as 79 of one ormore projections 77 extending from the bail 76 so that for eachengagement the bail is moved to the second position of operation tocause a spring contact 91 to engage a second spring contact 92 toestablish an electric circuit to an indicating means. The indicatingmeans proper (not shown) may comprise, for example, anelectro-magnetically operated rotary switch which is arranged to stepfrom one contact making position to another contact making position foreach operating pulse applied thereto via contact 91 and 92. Selectedcontact positions may be arranged to give visual or aural indicationsthat predetermined positions of the type-printing head 1 have beenreached. Shock absorbing devices 101 and 102 may be utilised to retardand arrest the motion of the carriage 2 toward the termination of itsmovements in the letter-feed and carriage-return directions.

It is now proposed to describe the co-action of component units of theapparatus in operation.

In the rest condition of the apparatus, the carriage 2 (FIG. 1) and thetype printing head 1 accommodated thereon are fully to the left of theapparatus prepared for a letter feed operation, or operations, havingbeen brought to rest at the end of a previous carriage-return operation,in a manner later to be described, so that the hydraulic valve andelectric circuit means constituted by contacts 65 and 66 of thecarriage-return selector means (FIG. 5) have been set to their firstconditions of operation. In the first condition of operation of thehydraulic valve the hydraulic clutch is rendered ineffective to engagethe drive between motor 59 and pulley wheel 40, since the piston 61 ofthe hydraulic valve is so positioned within the cylinder 63 that theinlet port to this cylinder from a feed line 96 and the pump 8 isblocked off by the lower end of the piston and the utilised hydraulicmedium fed under pressure from the pump is prevented from passingthrough the cylinder 63 to cylinder 52 (FIGS. 4 and 5) of the hydraulicclutch by way of feed line 5-3, but permitted to flow back to a sump viasump return feed line 106. There is therefore no pressure of hydraulicmedium exerted on piston 51 within cylinder 52 and in consequence nothrust is exerted by the piston 51 on the other integers constitutingthe hydraulic clutch to lock pulley 40 onto shaft 45, the drive betweenmotor 5% (FIG. 4) and the pulley 40 is therefore disengaged. However, in

this first condition of operation of the electric circuit means,electrical connection is established between contacts 65 and 66 thereof,and the magnetic clutch 56 will be energised to engage the drive betweenmotor 54 and pulley wheel 40 by way of coupling 55- and gear wheels 57,58, and 50. The carriage 2 (FIG. 1) and the typeprinting head wouldtherefore tend to be moved in the letter feed direction by the belt 39driven by pulley wheel 40. This movement is however prevented throughthe action of whichever one of pawls 9 and (FIG. 2) is in engagementwith a tooth such as 11 of the ratchet wheel 7 and through slippage ofmagnetic clutch 56 the degree of energisation of which is such thatalthough slippage occurs when restraint is applied to lead-screw 5sufficient power is transmitted by the magnetic clutch 56 to drive thecarriage 2 (FIG. 1) and type-printing head 1 when there is no suchrestraint. When at some later time a letter-feed signal is applied tothe solenoid 34 (FIG. 3) of the head-feed selector, the armature 32 isattracted by the magnetisable core 33, and pin 35 is withdrawn fromengagement with the underside of piston 29 in cylinder 39 which pistonis then self-actuating from a first condition of operation to a secondcondition of operation in the direction indicated by the arrow L underthe influence of compression spring 31. The utilised hydraulic medium isthen permitted to flow under pressure from the pump 8 (FIG. 5) via theprimary feed line 96, cylinder 39, the annular groove 95 in piston 29within cylinder 30, primary feed line 94 and secondary feed lines 97 and98 (FIG. 2) to cylinders 20 and 21. This flow of hydraulic medium causespistons 25 and 23 to move in the directions indicated by the arrows Hand I to move pawl 9 and 10 out of the path of the teeth such. as 11 ofthe ratchet wheel 7 by way of their carriers 12 and 13 respectively, andagainst the influence of springs 14A and 15A. Thus whichever one ofpawls 9 and 10 is in engagement with a tooth of the ratchet Wheel 7 thatparticular pawl is withdrawn clear of the tooth, and since restraint onthe lead-screw 5 is removed the carriage 2 (FIG. 1) and the typeprinting head 1 are permitted to move a step in the letter-feeddirection. Termination of the step movement is effected by the action ofthe pin 36 (FIG. 3) of the head-feed selector means, which pin is causedto move upward by the cam 37 on shaft 38 and which cam is continuouslyrotating to cause the pin 36 to reciprocate at a rate commensurate withthe letter-feed rate. The

in the same direction against the influence of compression spring 31,whereupon the lower end of piston 29 blocks off the port to cylinder 30from primary feed line 96 and the pump 8 (FIG. 1) and maintains the exitport from cylinder 30 to primary feed line 94 open with respect to asump return feed line 99 via annular groove 95 in piston 29. Pawls 9 and10, by way of their carriers, are then enabled to pivot on pins 14 and15 respectively and move back in the directions indicated by the arrowsE and F into the path of the teeth of the ratchet wheel 7 under theinfluence of springs 14A and 15A. This movement of pawls 9 and 10 andtheir carriers 12 and 13 cause pistons 23 and 25 to move in the samedirections, and the utilised hydraulic medium fed to cylinders 20 and 21is then forced back through secondary feed lines 26 and 27 and primaryfeed line 94 to the sump return feed line 99 (FIG. 3), via the annulargroove 95 in piston 29. It will be readily understood that as long as aletter-feed signalis applied to solenoid 34 (FIG. 3) the combinedeffects of the reciprocation of pin 36 and compression spring 31 onpiston 29 will result in recipropulses which are utilised to permit theapplication of a series of letter-feed signals to be applied to solenoid34, and also to permit application of signals to the operating means forselecting a combination of impression forming sections of a mosaictypeaprinting head which forms no part of the present invention.

During step-'by-step movement of the carriage 2 and type-printing head 1in the letter-feed direction the vertical surface 89 of a projection 90extending vertically upward from the carriage 2 engages the verticalsurface such as 79 of one or more projections 77 extending from the bail76 so that for each engagement the bail is moved to the second positionof operation to cause spring contact 91 to engage a second springcontact 92 to establish an electric circuit to the aforementionedindicating means (not shown). Movement of the bail, on each engagementbetween the projections 77 extending therefrom and the projection 90extending from the carriage 2, results in movement of the bail upward byway of the inclined planar surfaces and 81 moving with respect to therollers 34 and 85 rotatably afiixed to the frame of the apparatus. Thelatter mentioned movement of the bail results in disengagement occurringbetween a projection 77 extending from the bail and the projection '90extending from the carriage 2. The natural resilience of the springcont-act 91 and the weight of the bail 76 causes the bail to move towardthe left hand end of the apparatus whereupon disengagement betweenspring contacts 91 and 92 occurs, and the electrical contact to theindicating means is disestab-lished. Toward the end of movement of thecarriage 2 in the letter feed direction, the piston 86 is operated tomove in the direction indicated by the arrow A under the influence ofthe utilised hydraulic medium, the bail 76 therefore moves in the samedirection and the projections 77 extending therefrom are raised clear ofthe projection 90 extending from the carriage 2, to allow for freemovement of the carriage 2 and the type printinghead 1 in thecarriage-return direction.

On the cessation of the application of the letter-feed signal tosolenoid 34 (FIG. 3), the armature 32 of the solenoid will move clear ofthe core 33 under the influence of a'leaf-spring portion of thearmature. The pin 36 extending from the armature is therefore interposedinto the path of the reciprocating piston 29 which is then held up bythe pin 36 in its non-actuated position and'the pawls 9 and 16 are inconsequence interposed into the path of the teeth of the ratchet wheel7. As a result, one or the other of the pawls engages with a tooth ofthe ratchet wheel 7 and arrests further movement of the carriage 2(FIG. 1) and the type printing head 1 in the letter-feed direction.Toward the end of the latter mentioned movement and in response to acarriage-return signal, solenoid 68 (FIG. 5) of the carriage-returnselector means is energised and the armature 70 thereof is attracted ina clockwise direction about the axis of pin 72 and against the influenceof tension spring 73 to assume the position shown in dotted lines. Thelower end of the armature is thus withdrawn from contact with aprojection extending from the upper side of the righthand end of lever71, which lever then piVOts in an anti-clockwise direction about theaxis of the pin 7 4-. In consequence of this pivoting action of lever71, compression spring 64 causes selfactuation of both the hydraulicvalve and electric circuit means co-acting therewith to their secondconditions of operation. 7 In the second condition of operation of theelectric circuit means, the electrical connection between springcontacts 65 and 66 is disestablished and the magnetic clutch 56 (FIGS. 1and 4) is deenergised. The drive between motor 54 and pulley 40 is inconsequence disengaged, and movement of the upper portion of the belt39, the carriage 2 (FIG. 1) and the type printing head 1 in theletter-feed direction ceases.

In the second condition of operation of the hydraulicvalve, the drivebetween motor 59 (FIG. 4) and the pulley 40 (FIGS. 1 and 4) is engagedthrough the movement of piston 51 in cylinder 52 under the influence ofthe utilised hydraulic medium, which medium is allowed to flow underpressure from the pump 8 (FIG. 1) to cylinder 52 via primary feed line96 (FIG. 5) annular groove 75 in piston 61, primary feed line 28 andsecondary feed line 53. Movement of piston 51 causes it to engagepressure pad 47 to exert a thrust on this pressure pad and also frictionpad 49, pulley 4t and gear wheel 50 afiixed thereto, friction pad 48 andpressure pad 46. The integral collar 60 on shaft 45 opposes this thrustand in efiect locks pulley 4d and gear wheel 55) aflixed thereto to theshaft 45. In consequence of this locking action, motor 59, which isrunning continuously during operation of the apparatus, drives pulley 40in an anti-clockwise direction which in turn drives the upper portion ofbelt 39 in the direction indicated by the arrow B so as to move thecarriage 2 (FIG. 1) and the type-printing head in the carriage-returndirection. On the changeover from first condition of operation to secondcondition of operation of the hydraulic valve and electric circuit meansof the carriage-return selector means, the utilised hydraulic medium isalso allowed to flow under pressure from the pump 8 via primary feedline 96, the cylinder 63 by way of the annular groove 75 in piston 68,primary feed line 28, and thence to secondary feed lines 26 and 27(FIGS. 2 and 5) and secondary feed line 88 (FIGS. 1 and 2). Secondaryfeed line 88 is connected to cylinder 87 (FIG. 1) and thus piston 86 isoperated in the direction indi cated by the arrow A and since it is inengagement with the end of the bail '76, the bail is moved in the samedirection and upward so that all of the projections 77 extendingtherefore are held clear of projection 90 extend ing from the carriage 2for the whole of the period of movement of the carriage in thecarriage-return direction. Since secondary feed lines 26 and 27 (FIGS. 2and 5) are connected to cylinders 20 and 21 (FIG. 2), pistons 23 and 25,via pistons 22 and 24, are operated in the directions indicated by thearrows H and I respectively. Movement of these pistons cause pawls 9 and10 to be moved 'by way of their respective carriers 12 and 13 againstthe influence of the springs 14A and 15A in the directions reverse tothose indicated by the arrows E and F respectively, clear of the path ofthe teeth of the ratchet wheel 7 so that there is no restraint onmovement of the carriage 2 (FIG. 1) and the type-printing head 1 in thecarriage-return direction.

Movement of the carriage 2 (FIG. 1) and the typeprinting head 2 in thecarriage-return direction continues until the projection 93 on thecarriage 2 engages with the under side of the left hand end of the lever71 (FIG. 5). The lever 71 is then caused to pivot about the axis of pin74 to move the spindle 62 and piston 61 of the hydraulic valve upward.The hydraulic valve and electric circuit means are therefore returned totheir first conditions of operation and in which conditions the drivebetween motor 59 and pulley td is disengaged, and the spring contact 65is brought into engagement with spring contact 66. Engagement ofcontacts 65 and 6 6 energise magnetic clutch 56 (FIGS. 1 and 4) whichclutch then engages the drive between motor 54 and pulley wheel 40 viagears 57, 58 and 50. However, movement of the carriage 2 (FIG. 1) andthe type-printing head 1 in the letter feed direction is prevented sincein the first condition of operation of the hydraulic valve, the lowerend of piston 61 (:FIG. 5) blocks off the port to cylinder 63 fromprimary feed line 96 and maintains the exit port from cylinder 63 toprimary feed line 28 open with respect to a sump feed line 109 to thesump (not shown). The pressure of the utilised hydraulic medium, actingon pistons 23 and (FIG. 2) by Way of pistons 22 and 24 via secondaryfeed lines 2 6 and 27, is therefore removed and pawls 9 and '10 moveinto the path of the teeth of ratchet wheel 7 under the influence of thesprings 14A and 15A, one or the other of the pawls therefore engages atooth of the ratchet wheel, and the lead-screw 5 is restrained fromrotation and movement of the carriage 2 (FIG. 1) and the type printinghead 1 in the letter-feed direction is prevented, since in the firstcondition of operation of the hydraulic valve, the lower end of piston61 (FIG..5) blocks oif the port to cylinder 63 from primary feed line 96and maintains the exit port from cylinder 63 to primary feed line 28open with respect to a sump feed line to the sump (not shown). Thepressure of the utilised hydraulic medium, acting on pistons 23 and 25(*FIG. 2) by way of pistons 22 and 24 via secondary feed lines 26 and27, is therefore removed and pawls 53 and 10 move into the path of theteeth of ratchet wheel 7 under the influence of the springs 14A and 15Aone or the other of the pawls therefore engages a tooth of the ratchetwheel, and the lead-screw 5 is restrained from rotation and movement ofthe carriage 2 (FIG. 1) and the type printing head 1 in the letter-feeddirection is prevented.

The hydraulic valve and electric circuit means of the carriage-returnselector means are meanwhile maintained in their first conditions ofoperation by lever 71 (FIG. 5) which during its pivoting action in theclockwise direction about the axis of pin 74 permtited the armature 70to pivot about the axis of pin 72 so that it moved back to its originalposition, shown in full lines, under the influence of compression spring73. In this position, the lower end of the armature 70 engages with theprojection extending from the upper side of the right hand end of lever71 and maintains the lever pivoted in the clockwise direction.

Return of the hydraulic valve of the carriage-return selector means toits first condition of operation permits the utilised hydraulic mediumto flow back from cylinders 20 and 21 (FIG. 2), from cylinder 87 (FIG.1), and from cylinder 52 (FIGS. 1 and 4) via their respective secondaryfeed lines, primary feed lines 28, cylinder 63 and sump return feed line100 to the sump (not shown). Release of pressure of the utilisedhydraulic medium on piston 86 in cylinder 87 (FIG. 1) permits the piston86 to move Within the cylinder 87 to the left of the apparatus under theinfluence of the moving mass of the bail 76 of the indicating meanswhich then returns to its first condition of operation.

'It is to be understood that the foregoing description of specificexamples of this invention is not to be considered as a limitation onits scope.

What we claim is:

1. Type printing telegraph apparatus including a type printing headmounted on a carriage, power driven means for traversing the saidcarriage, lead-screw means rotatable by the said'carriage during itstraverse, a ratchet wheel afiixed to said lead-screw, pawl meansalternately engaging and disengaging said ratchet wheel to permitstep-by-step movement of the said carriage in the letterfeed direction,and head-feed selector means for operating said pawl-means to permitsaid step-by-step movement.

2 Type printing telegraph apparatus as claimed in claim 1, includingcarriage-return selector means for operating said pawl means to permitsaid movement of the carriage in the carriage-return direction, and forreversing the direction of drive of said power driven means ontermination of said step-by-step and carriage return movementsrespectively.

3. Type printing telegraph apparatus as claimed in claim 2 in which saidpower driven means includes a belt, pulley means for supporting saidbelt for movement in the said letter-feed and carriage-returndirections, means for driving said belt and carriage in said letter feedand carriage-return directions respectively, by way of said pulley meansand first and second clutch means, means operable by saidcarriage-return selector means to simultaneously cause the engagement ofone of said clutches and the disengagement of the other of saidclutches.

4. Type printing telegraph apparatus as claimed in claim 3 in which saidfirst and second clutches are electrically and hydraulically operatedrespectively.

5. Type printing telegraph apparatus as claimed in claim 4 in which thesaid carriage-return selector means includes electric circuit means andhydraulic valve means co-acting in first conditions of operationthereof, to cause said electrically operated clutch means to beeffective and said hydraulically operated clutch means to be ineffectiveto efiect movement of said carriage in the letter-feed direction, andco-aoting in second conditions of operation in response to acarriage-return signal to cause said hydraulically operated clutch meansto be effective and said electrically operated clutch means to beineffective to effect movement of said carriage in the carriage-returndirection, lever means operated by said carriage towards the end of themovement thereof in the carriage-return direction to actuate saidhydraulic valve means and said electric circuit means to said firstconditions of operation, and solenoid means operating in response to acarriagereturn signal and co-act ing with said lever means to permitactuation of said hydraulic valve means and electric circuit means tosaid second conditions of operation.

6. Type printing telegraph apparatus as claimed in claim 5 in which saidpawl means comprises two pawls, separate spring means for moving eachsaid pawl into the path of teeth of said ratchet wheel, means operableduring the movement of said carriage in the letter feed direction formoving both said pawls simultaneously into and clear of the path of saidratchet wheel and means operable for the movement of said carriage inthe carriage-return direction for holding both said pawls clear of saidratchet wheel.

7. Type printing telegraph apparatus as claimed in claim 6 in which saidratchet wheel is arranged with respect to said pawls so that duringsuccessive movements of said pawls into the path of the teeth of saidratchet wheelthe said pawls alternately engage a tooth of the ratchetwheel.

8. Type printing telegraph apparatus as claimed in claim 7 in whichhydraulic shock absorbing means is provided for each said pawl to absorbthe shock of engagement of the said pawl with a tooth of the saidratchet wheel.

9. Type printing telegraph apparatus 'as claimed in claim 8 comprisinghydraulically operable means controlled by said head-feed selector meansfor moving said pawls clear of said ratchet wheel and allowing theirmovement into the path of said ratchet wheel, and controlled by saidcarriage-return selector means for moving said pawls clear of saidratchet wheel.

10. Type printing telegraph apparatus as claimed in claim 9 in whichsaid head-feed selector means comprises a solenoid in response to anysignal involving a step movement of said carriage, a cam, a hydraulicvalve so connected to said solenoid as to be operative from a tion toallow movement of said pawls into the path of said ratchet wheel.

11. Type printing telegraph apparatus as claimed in claim 10 includingmeans for indicating a predetermined position of the said type printinghead in its movement in the said letter-feed direction.

12. Type printing telegraph apparatus as claimed in claim 11 in whichsaid indicating means comprises a bail having a plurality of projectionsextending therefrom each of which projections is particular to apredetermined position of said type printing head in its movement withsaid carriage in the letter-feed direction and which bail is arranged ina first position to permit said projections extending therefrom toengage a portion of said type printing head, means for causing said bailand the projections extending therefrom to move to a second positionclear of said portion of the type printing head each time a projectionengages with said portion and for allowing said bail to return to saidfirst position, electric contact means operated by said bail each timean engagement takes place between a projection extending therefrom andsaid portion of the type printing head, and means for counting andindicating a predetermined number of operations of said electric contactmeans.

13. Type printing telegraph apparatus as claimed in claim 12 in whichsaid means for causing said bail and the projections extending therefromto move clear of said portion of said type printing head comprises aplural ity of rollers rotatably mounted on said apparatus each of whichrollers is arranged to engage one of a, plurality of inclined planarsurfaces of said bail and in which engagement of said type printing headcauses said bail to move from said first position to said secondposition by way of said inclined planar surfaces moving with respect tosaid rollers.

14. Type printing telegraph apparatus as claimed in claim 13 in whichhydraulic means is provided operable to move said bail to and maintainsaid bail in said second position during movement of said type printinghead with said carriage in the said carriage-return direction.

15. Type printing telegraph apparatus as claimed in claim 14 in whichsaid hydraulic means comprises a piston slidably mounted within acylinder and engaging said bail and in which operation of said piston inone direction causes said bail to move from said first position to saidsecond position and operation of which in the reverse direction permitssaid bail to return to the said second position.

16. Type printing telegraph apparatus as claimed in claim 15 in whichsaid piston is operated in said one direction and permitted to return insaid reverse direction by said hydraulic valve means of saidcarriage-return selector means operating in said second and firstconditions of operation respectively.

References Cited in the file of this patent UNITED STATES PATENTS2,505,729 Zenner Apr. 25, 1950

1. TYPE PRINTING TELEGRAPH APPARATUS INCLUDING A TYPE PRINTING HEADMOUNTED ON A CARRIAGE, POWER DRIVEN MEANS FOR TRANSVERSING THE SAIDCARRIAGE, LEAD-SCREW MEANS ROTATABLE BY THE SAID CARRIAGE DURING ITSTRAVERSE, A RATCHET WHEEL AFFIXED TO SAID LEAD-SCREW, PAWL MEANSALTERNATELY ENGAGING AND DISENGAGING SAID RATCHET WHEEL TO PERMITSTEP-BY-STEP MOVEMENT OF THE SAID CARRIAGE IN THE LETTERFEED DIRECTION,AND HEAD-FEED SELECTOR MEANS FOR OPERATING SAID PAWL-MEANS TO PERMITSAID STEP-BY-STEP MOVEMENT.